2 operators in a quiet room manipulate knobs to control excavators fixed on the ceiling of excavation chamber watching respective monitoring screens. Another screen shows detailed information of air conditions such as atmospheric pressure and gas content in the pressurized excavation chamber where underground water seepage is controlled.

When the excavation bucket becomes full with material, the operator sends a signal to the crane operator who hoists the bucket and discharges the material on a stand-by truck. When the truck becomes full with material, it moves to a barge moored 50m away and dumps the material on it. A barge transports the excavated material to a reclamation site designated by the Tokyo Metropolitan Government. No sea water contamination was found. Every step of work was carried out in order.

This construction method protects the health and safety of construction workers by eliminating the need for difficult manual labor under pressurized and confined working conditions. Also, construction time was drastically reduced. Daiho Corporation`s site representative, Mr. Kobayashi, explained that one of the

difficulties encountered during construction, was the settlement of the steel shell in the sea bottom following the installation of steel jacket which surrounds and fixes the shell. The shell is sunken step by step excavating sea bottom as mentioned above.